AQA · GCSE · Physics
Course version: 8463 · Version from Sept 2016
Students should be able to compare the hazards associated with…
Full specification wording
Radioactive contamination: Students should be able to compare the hazards associated with contamination and irradiation.
Comparing the two hazards needs three contrasts.
Checked against the AQA 8463 specification (opens in a new tab) on .
- Point 6 of 8
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
Comparing the two hazards needs three contrasts. First, what is present: irradiation is exposure to radiation, contamination is the unwanted presence of radioactive material on or inside a person or object. Second, duration: irradiation stops when the source is removed or shielded, while contamination keeps delivering a dose for as long as the transferred atoms go on decaying, which for a long half-life can be years. Third, which radiation matters: outside the body gamma is the bigger risk because it penetrates to organs, while contamination makes alpha the bigger risk because it is highly ionising and gets absorbed directly by tissue. That is why gloves are worn even though they cannot stop irradiation: they prevent transfer of material.
What earns the marks
- Irradiation being exposure to radiation while contamination is the unwanted presence of radioactive material on or inside the person or object.
- Irradiation ending when the source is removed, whereas contamination continues while the atoms decay.
- Contamination being the greater hazard inside the body because alpha radiation is absorbed by tissue.
- A gamma source being the greater external hazard because gamma passes through skin.
- Gloves preventing contamination even though they do not prevent irradiation.
Common mistakes and how to put them right
Using the two words interchangeably within the same answer.
Asserting that contamination is always worse without naming a radiation type or a timescale.
Claiming a lab coat or gloves shield a person from gamma radiation.
Describing only the difference in definition and never comparing the hazards, which is what the question asks.
Saying an irradiated person continues to be exposed after the source is put away.
Exam tips
- Set the answer out as paired statements, one sentence on irradiation followed by one on contamination, so each comparison is visible.
- Use a comparative connective such as 'whereas' in every pair; a list of facts about each is often not credited as a comparison.
- Bring in half-life if one is quoted, because it controls how long the contamination hazard lasts.
Try the lesson
The start of the Radioactive contamination: Students should be able to compare the hazards associated with contamination and irradiation. lesson, made from checked teaching notes for this specification point.
Have a go first
Which statement correctly describes a key difference between the hazards of radioactive contamination and irradiation?
Listen
Comparing the two hazards needs three contrasts. First, what is present: irradiation is exposure to radiation, contamination is the unwanted presence of radioactive material on or inside a person or object. Second, duration: irradiation stops when the source is removed or shielded, while contamination keeps delivering a dose for as long as the transferred atoms go on decaying, which for a long half-life can be years. Third, which radiation matters: outside the body gamma is the bigger risk because it penetrates to organs, while contamination makes alpha the bigger risk because it is highly ionising and gets absorbed directly by tissue. That is why gloves are worn even though they cannot stop irradiation: they prevent transfer of material. A strong answer earns marks for these points. irradiation being exposure to radiation while contamination is the unwanted presence of radioactive material on or inside the person or object. irradiation ending when the source is removed, whereas contamination continues while the atoms decay. contamination being the greater hazard inside the body because alpha radiation is absorbed by tissue. a gamma source being the greater external hazard because gamma passes through skin. Exam tip: Set the answer out as paired statements, one sentence on irradiation followed by one on contamination, so each comparison is visible.
Key words
Say what each word means before you turn the card.
irradiation
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contamination
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duration of exposure
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protective precautions
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See every definition
- irradiation
- Exposure to radiation, which stops when the source is removed or shielded.
- contamination
- The unwanted presence of radioactive material on or inside a person or object, which keeps delivering a dose for as long as the transferred atoms go on decaying.
- duration of exposure
- Irradiation stops when the source is removed or shielded, whereas contamination continues while the atoms decay, which for a long half-life can be years.
- protective precautions
- Gloves are worn even though they cannot stop irradiation, because they prevent transfer of material.
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